for me personally, my biggest problem with the people immigrating to the USA, is the language barrier with the ones that refuse to learn to speak english
i can understand not knowing english if you're just visiting some friends in the states, but you've got all these pregnant women traveling to the states to give birth (i think term is "anchor babies") where because the baby was born in the states, they can get their older children enrolled in school here and get on welfare/medicaid/medicare/foodstamps etc etc, and for many of these women, they never learn english where they have their oldest kid serve as translator when they have to speak to non-latinos, then you've got males that come here when they're in their early 20's looking for work, they get into minimum wage jobs, spend several decades here and they don't learn english either, that's horrendously wrong, these people should learn english if they're gonna be here

aside from the language barrier
i really have no problem with the fact that most of the immigrants are undocumentable illegals
illegal immagrants make so much less money for the same work than the people that are here legally that, if you want to get into an economic debate, the illegals are actually necessary for the American economy to function as it currently exists